Automobile steering knuckles play a very important role in automotive chassis. At present, more and more automobile steering knuckles are made of an aluminum alloy material, and in production and manufacture of the automobile steering knuckles, the automobile steering knuckles produced by adopting a differential-pressure casting process are increasingly favored by all automobile manufacturers and producers throughout the world with few internal defects, high mechanical properties and good appearance. Thus, the mold design of aluminum alloy differential-pressure steering knuckles seems very important. Most of automobile differential-pressure steering knuckle molds are produced and manufactured overseas. In recent years, domestic mold designing manufacturers also start to perform design and manufacture gradually.
At present, in the using process of existing differential-pressure molds, ejection rods cannot automatically reset after ejecting out castings, and the ejection rods are ejected back through mechanical return column devices after upper and lower molds are close to each other to complete mold closing. For common steering knuckles for which lateral pull core structures are not needed to be designed, the return devices have no problem. However, for the steering knuckles for which the lateral pull core structures are needed to be designed, severe problems often arise. The specific situation is that the ejection rods stay at ultimate positions after ejecting out from castings. When a next casting cycle begins, the ejection rods do not reset when mold closing of the upper mold begins and during mold closing; while the lateral pull core structures simultaneously move towards the inner sides of a mold core at the moment, if a certain ejection rod is rightly located at the upper portion of the pulled core, the ejection rod which does not return bumps against the pull core moving towards the inner side to cause mold damage, or even the differential-pressure design is damaged. In addition, due to the fact that a drop exists in automobile steering knuckle molding in the height direction, the lengths of the ejection rods are certainly different. When the long ejection rods and short ejection rods eject out the casting, the long ejection rods produce large deformations, the short ejection rods produce small deformations, and accordingly asynchronous release of the steering knuckle casting from upper mold core and casting surface scratching are caused. Due to the fact that the automobile steering knuckles are bearing parts, the bearing parts bear very large alternating stress loads and deformations in the high-speed running process of an automobile, and small scratches on the casting surface possibly cause casting cracks or even breakage. Therefore, if a device with an ejection mechanism making ejection rods resettable can be designed based on an original structure, the above problems arisen in actual production will be well solved.